Transit time amplifier tube having an attenuated delay line

ABSTRACT

A transit time tube, in particular a traveling wave amplifier tube has a delay line consisting of a hollow tube of circular inner cross-section which is divided by successive transverse elements into cells. At least some of the cells are attenuated by means of attenuating bodies consisting of material subject to losses, bodies being in direct contact with the walls of the hollow tube and possessing the form of segments of the hollow tube inner cross-section of the delay line. In each case two such attenuating bodies extend from opposite sides of the walls by the same amount toward the longitudinal axis of the delay line.

United States Patent [191 Gross TRANSIT TIME AMPLIFIER TUBE HAVING AN ATTENUATED DELAY LINE [76] Inventor: Franz Gross, Schwanseestrasse 50,

[30] Foreign Application Priority Data Oct. 23, 1972 Germany 2251887 Us. Cl 315/35; 315/36; 333/81 B 1m. c1. HOlj 25/34 Field of Search 315/35, 3.6; 333/22, 81 B References Cited UNITED STATES PATENTS 10/1964 Kyhl 315/3.5 X

12/1967 Rubert 315/35 l/l968 Ruetz et al 315/3.5

[ June 10, 1975 3,412,279 11/1968 Allen et a1. 315/35 3,453,491 7/1969 Cerko 315/35 3,602,766 8/1971 Grant 315/35 Primary Examiner-Alfred E. Smith Assistant Examiner-Saxfield Chatmon, Jr.

[57] ABSTRACT A transit time tube, in particular a traveling wave amplifier tube has a delay line consisting of a hollow tube of circular inner cross-section which is divided by successive transverse elements into cells. At least some of the cells are attenuated by means of attenuating bodies consisting of material subject to losses, bodies being in direct contact with the walls of the hollow tube and possessing the form of segments of the hollow tube inner cross-section of the delay line. In each case two such attenuating bodies extend from opposite sides of the walls by the same amount toward the longitudinal axis of the delay line.

5 Claims, 8 Drawing Figures TRANSIT TIME AMPLIFIER TUBE HAVING AN ATTENUATED DELAY LINE BACKGROUND or THE iNvENrIoN 1. Field of the Invention This invention relates to a transit field amplifier tube having a delay line which comprises a hollow tube of circular inner cross-section, and more particularly to such a structure in which the hollow tube is divided by successive transverse elements into cells, at least a few of which are attenuated by attenuating bodies consisting of lossy material, the bodies being in direct contact with the walls of the hollow tube.

2. Description of the Prior Art Traveling wave (TW) tubes of the aforementioned kind are known in various embodiments. For example, reference may be taken to the German patent application 1,541,091 which has been laid open to public inspection.

Because of the frequency dependence of the radial field distribution in a delay line, on the one hand, and the large amount of heat to be discharged from the attenuating material, on the other hand, is difficult to design and place wide band attenuating elements in such a delay line in a suitable manner. In an arrangement constructed in accordance with the aforementioned German patent application, the attenuating elements are held by special holders which project from the conductor walls, close to the electron beam, and are also brought into permanent thermal contact with the two adjacent cavity dividing walls by way of a flow of coolant. This type of line design demands high precision in production and is limited in concepts with flowing coolants of variable pressure, particularly when a plurality of attenuating elements are to be utilized.

SUMMARY OF THE INVENTION The object of the present invention is to provide a transit field amplifier tube, in particular a traveling wave amplifier tube of the aforementioned type, with an attenuating arrangement which acts on a wide band and which is free of the aforementioned disadvantages.

For the realization of this object, it is proposed, in accordance with the present invention, that the attenuating bodies possess the form of segments of the cavity inner cross section of the delay line, wherein in each case two such attenuating bodies extend from diametrically opposed parts of the walls toward the longitudinal axis of the delay line by the same amount,

In an amplifier tube constructed in accordance with the invention, the attenuating bodies are both current and field attenuating and therefore have at their disposal a high, wide band attenuating force. The heat loss which arises in the attenuating bodies is discharged on extremely short heat paths to the walls of the delay line, the attenuating bodies possessing a large area of contact and therefore a high heat contact with the easily coolable walls. Since the attenuating bodies are arranged opposite one another and extend toward the longitudinal axis of the delay line equal maximum amounts at the same level of the delay line, any asymmetry of the electromagnetic reaction due to the attenuating elements is avoided.

In a further development of the invention, it is provided that the maximum inward extents of the attenuating bodies arranged successively in the course of the delay line increases by stages, for example in accor dance with a cos rule. In this embodiment of a known high frequency adaptation of the attenuation, the attenuation bodies provided in accordance with the invention prove particularly advantageous. Attenuating bodies having a greater maximum width .5 develop a larger quantity of heat which, however. is at the same time discharged by way of a larger contact surface to the walls. This structure substantially avoids any danger to the tube in the form displacement and destruction by heat as a result of a temperature gradient.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description of preferred embodiments of the invention taken in conjunction with the accompanying drawings, on Y which:

FIG. 1 is a longitudinal sectional view of a first embodiment of a delay line of a traveling wave amplifier tube constructed in accordance'with the invention;

FIG. 2 is a transverse section of the delay line taken substantially along the line 11-" of FIG. 1;

FIG. 3 is a transverse sectional view of the apparatus of FIG. 1 taken substantially along the line III-III;

FIG. 4 is a transverse sectional view of the apparatus illustrated in FIG. 1 taken substantially along the line IVIV;

FIG. 5 is a longitudinal sectional view of a second embodiment of a traveling wave amplifier tube constructed in accordance with the invention, as viewed substantially along the line VV of FIG. 6;

FIG. 6 is a transverse sectional view of the apparatus illustrated in FIG. 5 taken substantially along the line VI-VI;

FIG, 7 is a transverse sectional view of the apparatus of FIG. 5 taken substantially along the lineVII-VII; and

FIG. 8 is a transverse sectional view of the apparatus of FIG. 5 taken substantially along the line VIII VIII.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The schematic illustration of a transit field amplifier tube constructed in accordance with the invention represented in FIG. 1 illustrates only the part of the delay line which contains the attenuating elements, this part of the delay line being referenced l in FIG. 1. All of the other parts of the tube which are not essential to the invention have been omitted. The delay line 1 comprises a hollow tube of circular inner cross section which is divided by transverse walls having alternating coupling slots 2 and slot coupled cavities 3.

The precise shape of the coupling slots 2 is shown in FIGS. 2 and 4. In the exemplary embodiment represented in FIGS. 1-4, the delay line 1 is a solid aligned block soldered or pressure welded from punched or photo-etched discs, more specifically alternating profile discs 4 and spacers 5. Here, the profile discs 4 forms the transverse wall serving to divide the cavities 3 and accommodates the electron beam opening 6 and the coupling slot 2, while the spacer 5 is provided with the profile of the cavities 3.

The amplifier tube is attenuated with attenuating bodies arranged along the longitudinal axis of the delay line. As more specifically illustrated in FIG. 3, the attenuating bodies 7 are in direct contact with the walls of the hollow tube (they are soldered to the walls) and in accordance with the invention form symmetrical segments of the circular inner cross section of the walls. The maximum width s, which is equal for both segments is more specifically referenced s, in FIG. 3.

Since, in the dimensions of the delay line of the represented exemplary embodiment the longest wave operating mode possesses the character of an interdigital or cavity mode, the pairs of attenuating bodies 7 which take the form of segments of circles and which are arranged opposite one another are arranged between two adjacent coupling slots 2, thus in the cavities. In this arrangement, with the operating mode in question, the attenuating bodies 7 are at a position of high field strength and developing particular attenuating force for the undesired band edge oscillations, which are then pure interdigital and cavity modes.

FIG. 5 illustrates a second exemplary embodiment of a transit field amplifier tube constructed in accordance with the invention which differs from the first exemplary embodiment only in respect of the shape of the coupling slots 2 of the delay line 1. Again, only the part of the delay line containing the attenuating bodies 7 has been illustrated, this time in a longitudinal section whose sectional plane is perpendicular to that shown in FIG. 1 for purposes of clarity. In this type of delay line which has relatively large coupling slots 2, the longest wave operating mode is a type of slot mode. To again allow the attenuating bodies provided in accordance with the invention to act at a point of high field strength, and to attenuate band edge oscillations with particular strength, in this embodiment of the invention the pairs of attenuating bodies 7, arranged opposite one another, are in each case soldered to the walls of the hollow tube 4 at the level of the coupling slots 2.

In both of the exemplary embodiments disclosed herein, the attenuating bodies 7 have, for production reasons, been soldered to only one of the two different types of discs, either only to the spacer discs 5 (first exemplary embodiment) or only to the profile discs 4 (second exemplary embodiment). A very simple assembly of the attenuated delay line is in fact possible if the attenuating bodies are first inserted into one of the two different types of discs, and the discs are then fastened together to form an aligned structure.

The present invention is not limited to the embodiments specifically represented herein. In particular, the position of the attenuating elements proposed in accordance with the invention is not governed by the mode of band edge oscillations.

Although I have described my invention by reference to specific embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications which may reasonably and properly be included within the scope of my contribution to the art.

I claim:

1. A transit time amplifier tube comprising a delay line including a hollow tube of circular inner cross section, said tube divided by successive transverse elements into cells, attenuating bodies in at least a few of said cells, said bodies consisting of material subject to losses and said bodies mounted in direct contact with the walls of said hollow tube, said attenuating bodies acting on a wide frequency band and having the form of segments of said circular inner cross section of said hollow tube and two of such bodies extending from opposite parts of said walls toward the-longitudinal axis of the delay line by the same width.

2. A transit field amplifier tube as claimed in claim 1, wherein said attenuating bodies are provided with different increasing maximum widths successively in the course of said delay line.

3. A transit field amplifier tube as claimed inclaim 1, wherein said delay line possesses an interdigital or cavity mode as the longest wave operating mode, and said attenuating bodies are arranged between adjacent transverse elements of the delay line. a

4. A transit field amplifier tube as claimed in claim 1, wherein said delay line possesses a slot mode as the longest wave operating mode, some of said elements including coupling slots, and said attenuating bodies are in each case arranged at the level of the coupling slots as viewed in the longitudinal direction of the delay line.

5. A method of producing a delay line for a transit field amplifier tube consisting of a series of alternating profile discs and spacer discs, comprising the steps of first mounting attenuating bodies into one of the two different types of discs said attenuating bodies acting on a wide frequency band, arranging the discs in the form of alternate profile and spacer discs, and fastening the arranged discs to form an aligned block. 

1. A transit time amplifier tube comprising a delay line including a hollow tube of circular inner cross section, said tube divided by successive transverse elements into cells, attenuating bodies in at least a few of said cells, said bodies consisting of material subject to losses and said bodies mounted in direct contact with the walls of said hollow tube, said attenuating bodies acting on a wide frequency band and having the form of segments of said circular inner cross section of said hollow tube and two of such bodies extending from opposite parts of said walls toward the longitudinal axis of the delay line by the same width.
 2. A transit field amplifier tube as claimed in claim 1, wherein said attenuating bodies are provided with different increasing maximum widths successively in the course of said delay line.
 3. A transit field amplifier tube as claimed in claim 1, wherein said delay line possesses an interdigital or cavity mode as the longest wave operating mode, and said attenuating bodies are arranged between adjacent transverse elements of the delay line.
 4. A transiT field amplifier tube as claimed in claim 1, wherein said delay line possesses a slot mode as the longest wave operating mode, some of said elements including coupling slots, and said attenuating bodies are in each case arranged at the level of the coupling slots as viewed in the longitudinal direction of the delay line.
 5. A method of producing a delay line for a transit field amplifier tube consisting of a series of alternating profile discs and spacer discs, comprising the steps of first mounting attenuating bodies into one of the two different types of discs said attenuating bodies acting on a wide frequency band, arranging the discs in the form of alternate profile and spacer discs, and fastening the arranged discs to form an aligned block. 